function [v2,path]=ssg_prox_nag(ssg,prox,init,theta)
iter=1e5;
randn('seed',0);
v1=init;
dim=length(init);
v2=v1+randn(dim,1);

path=zeros(dim,iter);
dis=theta;
for i=1:iter
    a=1/(i+3)^(8/9)/16;
    theta=dis/(i+3);
    x=(1+theta)*v2-v1*theta;
    v1=v2;    
     z=prox(x,a);
    % z=x-a*sign(x);
    v2=z-a*ssg(z);
    path(:,i)=x;
end
